There are known in the prior art various systems for applying coatings of different materials to articles for a variety of reasons. For example, optical articles, such as goggle lenses, visors and the like, have coatings of synthetic resin applied thereto in an effort to increase resistance to abrasion.
One coating composition of the prior art especially adapted for use on synthetic resins to increase the scratch resistance thereof, is a composition formed from polysilicic acid and a copolymer of chlorotrifluorethylene or tetrafluoroethylene and a vinyl ether made and sold by E. I. DuPont de Nemours & Company under the registered trade mark "ABCITE". While this coating solution is generally satisfactory for use on synthetic resins which replace glass in certain applications, difficulty has been experienced in applying the material to optical bodies such as visors and lenses and the like in such a way as will not interfere with the optical properties thereof. In systems of the prior art for applying such coatings, the resultant coating incorporated a number of undesirable physical occlusions and was not optically distortion free. Attempts to build up relatively thick coatings by multiple applications of the solution resulted in haze. In addition to the difficulties pointed out hereinabove, the solution as used in processes of the prior art deteriorated relatively rapidly so that its useful life was only about 10 days.
We have invented a method of and apparatus for coating articles which overcomes the defects of coating systems of the prior art. Our system enables us to apply a clear, optically distortion-free protective coating to an article such for example as a molded synthetic resin lens. The coating resulting from our process has a minimum number of physical occlusions. Our process and apparatus permit us to build up a thick, clear coating in a single application of the coating solution. Our method and apparatus appreciably extend the life of the coating solution.